1. Field of Endeavor
The present invention relates to the field of gas turbine technology, more specifically to a blade for a gas turbine, and to a method for producing such a blade.
2. Brief Description of the Related Art
The hot gas temperatures, which are becoming ever higher, in gas turbines make it necessary to not only produce the rotor blades and/or stator blades in use from special materials but also to cool the blades in an efficient manner using a cooling medium. In this case, the cooling medium is introduced into the interior of the blades, flows through cooling passages which are arranged in the walls, and discharges to the outside through film-cooling holes in order to form a cooling film on the outer side of the blade at the places which are thermally particularly loaded.
The current status of blade cooling technology is known from U.S. Pat. No. 6,379,118 B2, for example. Cooling passages in the walls are used there in combination with impingement cooling, turbulence-generating elements, backflow. and film cooling in order to keep the wall temperatures down so that a satisfactory service life of the components is achieved.
The prior art which is described in that patent has various disadvantages, however:
the spacing of the film-cooling holes cannot be freely selected in order to balance out the different cooling mechanisms (film cooling and internal cooling) because a strict sequence of cooling passages and film-cooling holes is observed;
there is no possibility of protecting the rear wall while introducing the film-cooling holes; and
there is no existing method for the purpose of cooling the fillets between the blade airfoil and the platform, which are particularly critical for the service life.